Parker's S4 solenoids are the refrigeration industry’s standard for solenoid valves and have provided decades of safe and reliable operation. These valves are highly configurable and can be provided with flanges for Socket Welding, Butt Welding, ODS connections, and Threaded connections. The S4 is offered in sizes from ¾” (DN20) to 8” (DN200). These valves may be opened by means of the manual opening stem for servicing or in case of electrical power failure. As the S4 valves up to 4” feature a flanged connection they may be easily removed from the system for servicing. The S4 valves are pilot operated and require a minimum 0.21 bar (3 psi) pressure drop to fully open. The S4AD is a spring closing, pilot operated, dual-position solenoid valve which is crucial for evaporator control groups that use hot gas defrost. The dual position function of the S4AD allows the system to equalize before fully opening and can prevent liquid hammer. The S4X is an explosion proof hazardous environment type solenoid carrying a NEMA Type 4 and 7 classification.